Place the watercress in a 10-inch pie plate or quiche dish.,Cook, uncovered, at 100 percent power for 5 minutes 30 seconds in a microwave oven.,Remove from the oven and let stand until cool.,Place the watercress in a food processor and coarsely chop.,Remove to a large mixing bowl.,Place the onion and garlic in the food processor and finely chop.,______,Transfer the mixture to a glass loaf pan measuring 9 by 5 by 3 inches, making sure there are no air pockets.,Cover tightly with microwave plastic wrap and cook at 100 percent power for 14 minutes.,Prick the plastic to release steam.,Remove from the oven and uncover.,Cover with a kitchen towel and let stand for 10 minutes.,Serve hot or cold.